1.
Generally the following summary link contains information about recommended tools.
Please look at sections "Hardware Development Tools".
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=i.MX6Q&fpsp=1&tab=Design_Tools_Tab
Please consult with JTAG tool / probe provider about i.MX6 initialization scripts.
Also please pay attention :
The JTAG_MOD pin of the JTAG connector controls the selection of JTAG to the core logic or
boundary scan operation. For software debugging The JTAG_MOD should be pulled
down.
2.
ARM RealView and DS-5 support i.MX6.
http://www.arm.com/products/tools/software-tools/ds-5/index.php
http://www.arm.com/products/tools/software-tools/rvds/index.php
The next JTAG probes may be applied : RealView ICE and DSTREAM.
http://www.arm.com/products/tools/debug-adapters/rvi-rvt2.php
Also please find an overview of 3rd party development tools for ARM here:
http://www.freescale.com/files/wireless_comm/doc/brochure/BRTOOLENABLECO.pdf
The next app note may be useful in debugging :
"AN4553 Using Open Source Debugging Tools for Linux on i.MX Processors."
http://cache.freescale.com/files/32bit/doc/app_note/AN4553.pdf